Capability Development in High Strength and Conductivity Aluminium Alloys for Powder Bed Fusion – Laser Beam (PBF-LB)

Aluminium alloys currently adopted for powder bed fusion – laser beam (PBF-LB), especially aluminium-silicon (Al-Si) based alloys, typically struggle to compete with the high strength exhibited by conventionally manufactured aluminium alloys such as 7075. Additionally, Al-Si based systems show reduced thermal and electrical conductivity compared to purer aluminium compositions such as the 1xxx series. The potential for lightweight components especially for space, aerospace, and automotive applications as well as the advantages of physical properties improvements for functionality in motors or heat exchangers are major drivers for developing new aluminium alloys for additive manufacturing (AM). To expand the aluminium-based alloy portfolio for PBF-LB at the MTC, several alloys ranging from high strength to high thermal conductivity have been investigated in detail and include A20XTM (ECKART), Aheadd® CP1 (Constellium), Addalloy 5T & 7S (NanoAl) as well as a novel 7xxx composition (General Motors). Initial powder characterisation was carried out prior to in-depth parameter development using minitab, analysis methods included Archimedes density, optical microscopy, fracture surface analysis and EBSD. Mechanical property benchmarking included room temperature (and elevated temperature) tensile and High Cycle Fatigue testing. Final demonstrator structures were manufactured specifically aligned to electrification applications that benefited from increased strength and conductivity, this included an electric motor housing with topology optimized features and an assembled stator pack with additively manufactured motor windings.